The present invention relates to a lubricant composition having improved performance properties.
Lubricant compositions such as motor oils have been the subject of much research to improve their physical and chemical properties. For instance viscosity index modifiers, which are generally polymers, have been used for many years to provide oils with useful viscosity at both high and low operating temperatures. New and improved VI modifiers are continually being introduced. There are also corrosion inhibitors which are used in lubricants in order to prevent damage to the lubricated parts, particularly when they are subjected to corrosive byproducts of combustion. In many instances these and other lubricant additives interact with each other in ways which are not predictable. Thus the use of certain VI modifiers, especially nitrogen-containing dispersant VI improvers, can result in increased corrosion when used with ordinary corrosion inhibitor compositions. Now, however, a corrosion inhibition package has been found which leads to improved corrosion properties when these selected VI modifiers are employed.
U.S. Pat. No. 3,087,936, LeSuer, Apr. 30, 1963, discloses the reaction product of an aliphatic olefin-polymer-succinic acid producing compound with an amine and reacting the resulting product with a boron compound. The composition is useful as an additive in lubricants.
U.S. Pat. No. 4,522,785, D'Errico, Jun. 11, 1985, discloses dialkylaminomethyl aromatic triazoles as corrosion inhibitors.
U.S. Pat. No. 5,049,293, Blain et al., Sept. 17, 1991, discloses an additive for lubricant or fuel composition comprising the boronated reaction product of polyalkenyl substituted succinimides, aldehydes and triazoles. The substituted succinimide, aldehyde, and triazole are reacted at 100.degree.-200.degree. C. at ambient pressure. The reaction product is then borated by reaction with e.g. boric acid.
U.S. Pat. No. 4,948,542, Kapuscincki et al., Aug. 14, 1990, discloses a dispersant anti-oxidant VI improver for a lubricating oil composition. The additive is prepared by reacting a polymer prepared from ethylene and at least one C.sub.3 -C.sub.10 alpha-monoolefin with a nitrosodiphenylamine compound.